Designed by Experts, Proven by Champions. The Achilles ATR-K Sport is a street-legal tire born in the field of track racing. Proven by Champions in Touring series all around the world, ATR-K Sport features an aggressive design for your track-racing needs and would still take you back home safe and sound. Specially designed to maximize grip and minimize energy loss during cornering, and the thread design ensures that maximum contact is made between the tires and the ground, giving you fast lap times and one huge grin on your face!